Field of the Invention
Embodiments of the invention relate to a synchronous statically indeterminate mesh-beam excitation large-scale vibrating screen, which is especially suitable for depth grading, dewatering, medium drainage and desliming of wet and sticky raw coal, and grading of other materials.
Description of the Related Art
Vibrating screens are the major equipment in coal preparation plants, and the quantity of the vibrating screens is large, the norms of the vibrating screens are various, even the accidents related to the vibrating screens are frequent.
Large-scale vibration grading screens are the key equipment for construction of new large-scale coal preparation plants, and key equipment for technical renovation of existing coal preparation plants. The reliability of these screens has direct influence on the normal production and economic benefit of the coal preparation plants. Up to now, there is no great breakthrough in the research and development of the structure of large-scale vibrating screens yet. Large-scale vibrating screens produced by domestic manufacturers cannot meet the actual demands of production in coal mines and coal preparation plants in terms of reliability and service life. Essentially, large-scale vibrating screens demanded in China depend on import.
In terms of the structural form and design techniques, all large-scale vibrating screens imported and assimilated technically in China employ gear-driven forcibly synchronized vibration exciters, in which the bearing beam is a single supporting bearer, and has a massive structure in order to withstand the impact load caused by high excitation force. When the section width of the screen frame is greater than 3 m, the structural dimensions and weight of the bearing beam will be increased greatly, and the vibration mass of the screen body will be increased accordingly. Consequently, it is difficult to process and assemble the bearing beam; in addition, the structural stiffness of a vibrating screen in such a structure is not strengthened, owing to the effect of concentrated load. Therefore, failures often occur during the operation of such vibrating screens. For example, the hollow beams may be fractured and the side plates may be cracked. Hence, not only the production efficiency is degraded, but also the service life of the vibrating screen is shortened. That is also a critical factor to limit the section width of screen body of vibrating screens to be larger and breakthroughs in the structural parameters for long. Since the screen size cannot be increased, more vibrating screen equipment have to be used to meet the demand of production. Consequently, the construction cost and production management cost are increased.
At present, all large-scale and extra-large-scale vibrating screens demanded in China depend on import. Over the years, how to solve the key problems in technology, research and develop large-scale vibrating screens with high reliability, and accomplish technical localization of large-scale vibrating screens have been urgent tasks in the development of coal preparation process technical level and large-scale industrial production.